Electrosynthesis and characterisation of novel poly(Nile blue)-deep eutectic solvent/Prussian blue nanoparticle modified electrodes and their biosensing application

Abstract

• Ethaline deep eutectic solvent (DES) for electropolymerisation of Nile blue (NB). • Poly(Nile blue) formed on Prussian blue nanoparticles on glassy carbon electrodes. • Electrochemical quartz crystal microbalance study of polymerisation process. • Electrochemical and surface characterisation of DES polymer modified electrodes. • Tyrosinase immobilised on PNB ethaline film gives superior biosensing of catechol. Electropolymerisation of Nile blue to form films of the redox polymer poly(Nile blue) (PNB) in ethaline deep eutectic solvent, by potential cycling, on Prussian-blue nanoparticle (PBNP) modified glassy carbon electrodes (GCE) is described. For comparison, PNB films were also prepared in aqueous solution. The performance of the novel composite modified electrodes was evaluated electrochemically (cyclic voltammetry, electrochemical impedance spectroscopy, and fixed potential amperometry). An electrochemical quartz crystal microbalance was used to quantify the amount of the polymer film deposited in ethaline and to investigate the polymerisation mechanism. The nanostructured morphology was examined using transmission electron microscopy and scanning electron microscopy. PNB ethaline /PBNP/GCE and PNB aqueous /PBNP/GCE were used as support for immobilising the enzyme tyrosinase for the biosensing of catechol, the biosensor configuration with the PNB film formed in ethaline being significantly more sensitive than that with the PNB film made in aqueous solution.